Workpiece damage produced by creep feed grinding

Abstract

The nature and extent of workpiece damage induced by creepfeed grinding a Nimonic alloy have been investigated. Undersevere burn conditions considerable surface and internal oxidation occurs, together with the formation of cracks penetrating to depths of 2mm. A white unetchable subsurface layer is also formed in which the γ’ precipitate is dissolved. Similar observations have been made for unburnt specimens, but here, the extent of the damage is much reduced. Heating after grinding causes reprecipitation of γ’ in the white layer formed under both conditions, and the formation of the deleterious sigma phase in the white layer produced during burn. It is suggested that high-cycle fatigue and low-stress creep behaviour will be the properties most affected in service by grinding damage.